A Study of Magnetic and Electrical Crossover Region of La sub (0.5+-delta) Ca sub (0.5+-delta) Mn0 sub 3
28 June 1999
The ground states of La sub (i-x) Ca sub x Mn0 sub 3 change from a double exchange associated conducting ferromagnet at (x0.50) even when x is varied only slightly around 0.50. We have performed a careful study of the electrical and magnetic properties of these materials for a range of samples with slightly varying calcium doping around x ~ 0.50. The nature of the ground state and the transition was not only found to be sensitive to the calcium doping but also to the actual MN sup (4+) content of these materials. The low temperature resistivity of the x ~ 0.50 materials below the charge ordering temperature was found to drop with decreasing temperature in the presence of magnetic fields of even a few tesla or a slight Ca underdoping (x